Main Content

The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 4797

Telesphore Sime-Ngando and Claude Alain Groliere; [Effets quantitatifs des Fixateurs sur la Conservation des Cilies Planctoniques d'Eau Douce] (Quantitative Effects of Fixatives on the Storage of Freshwater Planktonic Ciliates). Arch.Protistenk 140:109-120, 1991

Reprint

In File

Notes

This work describes the quantitative effects of fixatives on the storage of freshwater planktonic ciliates. Samples originated from a small eutrophic mountain lake (lac d'Aydat, France). Unconcentrated, filtered and centrifuged samples were preserved in five different fixatives: Mercuric chloride (HgCl2), Lugol, Formaldehyde, Glutaraldehyde, and Champy-Da Fano. Counts (in triplicates) were done over 9 months, with a periodicity of 3 months, and compared by simple regression between loss rate (Y) and storage time (X). Overall, mean losses after 3, 6, and 9 months of conservation were respectively 7.2, 16.4 and 30.7%. 15% of cells are destroyed between the 6th and 9th months of storage. Among the fixatives, HgCl2 was the best conservative for ciliates; it reduced by 9.7% the number of ciliates after 9 months of storage. Lugol was the most destructive fixative for ciliate conservation; the losses (57.9%) which we have obtained with this preservative were 2.6 fold higher than those due to other fixatives, after a 9 months storage. The three other fixatives reduced the ciliate number respectively around 10 and 26%, after 6 and 9 months conservation. Moreover, the ciliates which were first stressed (by filtration and centrifugation) before fixation, were 1.3 fold more sensitive to conservation than those of the unconcentrated samples, after 9 months storage. Oligotrichs and other taxa (concentrated or not) found in this study seem to be less affected during conservation than Scuticociliates, treated in the same conditions. In conclusion, we found that more than 6 months storage of freshwater planktonic ciliates should be avoided. Otherwise, a correction factor (20% for our samples) should be considered during data anaylsis.